Croatian Marble Cake (Mramorni Kolac)

A colleague at work shared this recipe with me. It's a marble cake made with olive oil. It's not too sweet and goes well with a cup of tea or coffee. It's easy to make and moist. I made this for a farewell morning tea for the asst. parish priest that we'll be having after Mass tomorrow.

Ingredients
4 eggs
2 cups of sugar
3 cups S.R flour, sifted
1 cup oil
1 1/2 cups of milk
1 rind of lemon and orange, grated
1 teaspoon cocoa

Method
1. Beat the eggs in an electric mixer. Slowly add in the sugar.
2. Once well beaten, add in the oil, milk, lemon and orange rind.
3. Fold in the sifted flour.
4. Divide the mixture into 3/4 and 1/4 sections into two bowls. In the 1/4 mixture, add the cocoa and mix well.
5. In a greased cake tin (9"/23cm square or Kugelhopf), place one scoop of each mixture alternately. (Note: the mixture is very liquid-like).
6. Place in a 160 degrees oven for about 40 minutes.
7. It can be served as is or dusted with icing sugar and served with a dollop of cream and strawberries.